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1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : /*
3 : * sysctl.h: General linux system control interface
4 : *
5 : * Begun 24 March 1995, Stephen Tweedie
6 : *
7 : ****************************************************************
8 : ****************************************************************
9 : **
10 : ** WARNING:
11 : ** The values in this file are exported to user space via
12 : ** the sysctl() binary interface. Do *NOT* change the
13 : ** numbering of any existing values here, and do not change
14 : ** any numbers within any one set of values. If you have to
15 : ** redefine an existing interface, use a new number for it.
16 : ** The kernel will then return -ENOTDIR to any application using
17 : ** the old binary interface.
18 : **
19 : ****************************************************************
20 : ****************************************************************
21 : */
22 : #ifndef _LINUX_SYSCTL_H
23 : #define _LINUX_SYSCTL_H
24 :
25 : #include <linux/list.h>
26 : #include <linux/rcupdate.h>
27 : #include <linux/wait.h>
28 : #include <linux/rbtree.h>
29 : #include <linux/uidgid.h>
30 : #include <uapi/linux/sysctl.h>
31 :
32 : /* For the /proc/sys support */
33 : struct completion;
34 : struct ctl_table;
35 : struct nsproxy;
36 : struct ctl_table_root;
37 : struct ctl_table_header;
38 : struct ctl_dir;
39 :
40 : /* Keep the same order as in fs/proc/proc_sysctl.c */
41 : #define SYSCTL_ZERO ((void *)&sysctl_vals[0])
42 : #define SYSCTL_ONE ((void *)&sysctl_vals[1])
43 : #define SYSCTL_TWO ((void *)&sysctl_vals[2])
44 : #define SYSCTL_THREE ((void *)&sysctl_vals[3])
45 : #define SYSCTL_FOUR ((void *)&sysctl_vals[4])
46 : #define SYSCTL_ONE_HUNDRED ((void *)&sysctl_vals[5])
47 : #define SYSCTL_TWO_HUNDRED ((void *)&sysctl_vals[6])
48 : #define SYSCTL_ONE_THOUSAND ((void *)&sysctl_vals[7])
49 : #define SYSCTL_THREE_THOUSAND ((void *)&sysctl_vals[8])
50 : #define SYSCTL_INT_MAX ((void *)&sysctl_vals[9])
51 :
52 : /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
53 : #define SYSCTL_MAXOLDUID ((void *)&sysctl_vals[10])
54 : #define SYSCTL_NEG_ONE ((void *)&sysctl_vals[11])
55 :
56 : extern const int sysctl_vals[];
57 :
58 : #define SYSCTL_LONG_ZERO ((void *)&sysctl_long_vals[0])
59 : #define SYSCTL_LONG_ONE ((void *)&sysctl_long_vals[1])
60 : #define SYSCTL_LONG_MAX ((void *)&sysctl_long_vals[2])
61 :
62 : extern const unsigned long sysctl_long_vals[];
63 :
64 : typedef int proc_handler(struct ctl_table *ctl, int write, void *buffer,
65 : size_t *lenp, loff_t *ppos);
66 :
67 : int proc_dostring(struct ctl_table *, int, void *, size_t *, loff_t *);
68 : int proc_dobool(struct ctl_table *table, int write, void *buffer,
69 : size_t *lenp, loff_t *ppos);
70 : int proc_dointvec(struct ctl_table *, int, void *, size_t *, loff_t *);
71 : int proc_douintvec(struct ctl_table *, int, void *, size_t *, loff_t *);
72 : int proc_dointvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
73 : int proc_douintvec_minmax(struct ctl_table *table, int write, void *buffer,
74 : size_t *lenp, loff_t *ppos);
75 : int proc_dou8vec_minmax(struct ctl_table *table, int write, void *buffer,
76 : size_t *lenp, loff_t *ppos);
77 : int proc_dointvec_jiffies(struct ctl_table *, int, void *, size_t *, loff_t *);
78 : int proc_dointvec_ms_jiffies_minmax(struct ctl_table *table, int write,
79 : void *buffer, size_t *lenp, loff_t *ppos);
80 : int proc_dointvec_userhz_jiffies(struct ctl_table *, int, void *, size_t *,
81 : loff_t *);
82 : int proc_dointvec_ms_jiffies(struct ctl_table *, int, void *, size_t *,
83 : loff_t *);
84 : int proc_doulongvec_minmax(struct ctl_table *, int, void *, size_t *, loff_t *);
85 : int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, void *,
86 : size_t *, loff_t *);
87 : int proc_do_large_bitmap(struct ctl_table *, int, void *, size_t *, loff_t *);
88 : int proc_do_static_key(struct ctl_table *table, int write, void *buffer,
89 : size_t *lenp, loff_t *ppos);
90 :
91 : /*
92 : * Register a set of sysctl names by calling register_sysctl
93 : * with an initialised array of struct ctl_table's. An entry with
94 : * NULL procname terminates the table. table->de will be
95 : * set up by the registration and need not be initialised in advance.
96 : *
97 : * sysctl names can be mirrored automatically under /proc/sys. The
98 : * procname supplied controls /proc naming.
99 : *
100 : * The table's mode will be honoured for proc-fs access.
101 : *
102 : * Leaf nodes in the sysctl tree will be represented by a single file
103 : * under /proc; non-leaf nodes will be represented by directories. A
104 : * null procname disables /proc mirroring at this node.
105 : *
106 : * The data and maxlen fields of the ctl_table
107 : * struct enable minimal validation of the values being written to be
108 : * performed, and the mode field allows minimal authentication.
109 : *
110 : * There must be a proc_handler routine for any terminal nodes
111 : * mirrored under /proc/sys (non-terminals are handled by a built-in
112 : * directory handler). Several default handlers are available to
113 : * cover common cases.
114 : */
115 :
116 : /* Support for userspace poll() to watch for changes */
117 : struct ctl_table_poll {
118 : atomic_t event;
119 : wait_queue_head_t wait;
120 : };
121 :
122 : static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
123 : {
124 0 : return (void *)(unsigned long)atomic_read(&poll->event);
125 : }
126 :
127 : #define __CTL_TABLE_POLL_INITIALIZER(name) { \
128 : .event = ATOMIC_INIT(0), \
129 : .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
130 :
131 : #define DEFINE_CTL_TABLE_POLL(name) \
132 : struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
133 :
134 : /* A sysctl table is an array of struct ctl_table: */
135 : struct ctl_table {
136 : const char *procname; /* Text ID for /proc/sys, or zero */
137 : void *data;
138 : int maxlen;
139 : umode_t mode;
140 : /**
141 : * enum type - Enumeration to differentiate between ctl target types
142 : * @SYSCTL_TABLE_TYPE_DEFAULT: ctl target with no special considerations
143 : * @SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY: Used to identify a permanently
144 : * empty directory target to serve
145 : * as mount point.
146 : */
147 : enum {
148 : SYSCTL_TABLE_TYPE_DEFAULT,
149 : SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY
150 : } type;
151 : proc_handler *proc_handler; /* Callback for text formatting */
152 : struct ctl_table_poll *poll;
153 : void *extra1;
154 : void *extra2;
155 : } __randomize_layout;
156 :
157 : struct ctl_node {
158 : struct rb_node node;
159 : struct ctl_table_header *header;
160 : };
161 :
162 : /* struct ctl_table_header is used to maintain dynamic lists of
163 : struct ctl_table trees. */
164 : struct ctl_table_header {
165 : union {
166 : struct {
167 : struct ctl_table *ctl_table;
168 : int used;
169 : int count;
170 : int nreg;
171 : };
172 : struct rcu_head rcu;
173 : };
174 : struct completion *unregistering;
175 : struct ctl_table *ctl_table_arg;
176 : struct ctl_table_root *root;
177 : struct ctl_table_set *set;
178 : struct ctl_dir *parent;
179 : struct ctl_node *node;
180 : struct hlist_head inodes; /* head for proc_inode->sysctl_inodes */
181 : };
182 :
183 : struct ctl_dir {
184 : /* Header must be at the start of ctl_dir */
185 : struct ctl_table_header header;
186 : struct rb_root root;
187 : };
188 :
189 : struct ctl_table_set {
190 : int (*is_seen)(struct ctl_table_set *);
191 : struct ctl_dir dir;
192 : };
193 :
194 : struct ctl_table_root {
195 : struct ctl_table_set default_set;
196 : struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
197 : void (*set_ownership)(struct ctl_table_header *head,
198 : struct ctl_table *table,
199 : kuid_t *uid, kgid_t *gid);
200 : int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
201 : };
202 :
203 : /* struct ctl_path describes where in the hierarchy a table is added */
204 : struct ctl_path {
205 : const char *procname;
206 : };
207 :
208 : #ifdef CONFIG_SYSCTL
209 :
210 : void proc_sys_poll_notify(struct ctl_table_poll *poll);
211 :
212 : extern void setup_sysctl_set(struct ctl_table_set *p,
213 : struct ctl_table_root *root,
214 : int (*is_seen)(struct ctl_table_set *));
215 : extern void retire_sysctl_set(struct ctl_table_set *set);
216 :
217 : struct ctl_table_header *__register_sysctl_table(
218 : struct ctl_table_set *set,
219 : const char *path, struct ctl_table *table);
220 : struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
221 : void unregister_sysctl_table(struct ctl_table_header * table);
222 :
223 : extern int sysctl_init_bases(void);
224 : extern void __register_sysctl_init(const char *path, struct ctl_table *table,
225 : const char *table_name);
226 : #define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
227 : extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
228 :
229 : void do_sysctl_args(void);
230 : int do_proc_douintvec(struct ctl_table *table, int write,
231 : void *buffer, size_t *lenp, loff_t *ppos,
232 : int (*conv)(unsigned long *lvalp,
233 : unsigned int *valp,
234 : int write, void *data),
235 : void *data);
236 :
237 : extern int pwrsw_enabled;
238 : extern int unaligned_enabled;
239 : extern int unaligned_dump_stack;
240 : extern int no_unaligned_warning;
241 :
242 : #define SYSCTL_PERM_EMPTY_DIR (1 << 0)
243 :
244 : #else /* CONFIG_SYSCTL */
245 :
246 : static inline void register_sysctl_init(const char *path, struct ctl_table *table)
247 : {
248 : }
249 :
250 : static inline struct ctl_table_header *register_sysctl_mount_point(const char *path)
251 : {
252 : return NULL;
253 : }
254 :
255 : static inline struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
256 : {
257 : return NULL;
258 : }
259 :
260 : static inline void unregister_sysctl_table(struct ctl_table_header * table)
261 : {
262 : }
263 :
264 : static inline void setup_sysctl_set(struct ctl_table_set *p,
265 : struct ctl_table_root *root,
266 : int (*is_seen)(struct ctl_table_set *))
267 : {
268 : }
269 :
270 : static inline void do_sysctl_args(void)
271 : {
272 : }
273 : #endif /* CONFIG_SYSCTL */
274 :
275 : int sysctl_max_threads(struct ctl_table *table, int write, void *buffer,
276 : size_t *lenp, loff_t *ppos);
277 :
278 : #endif /* _LINUX_SYSCTL_H */
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